On 12/14/2015 06:15 PM, Fred Cisin wrote:
I got in late. My first encounter with Centronics was TRS80 (1979?) At that time, Centronics did not yet have a monopoly on parallel "protocols", although the company had certainly been around for a while. Once they got the TRS80 market, and then the IBM PC market, any other designs faded away fast.
The other common interface was the Dataproducts--IMOHO, a much better one. The usual DP connector was a 4-row job (I don't know what the connector part number was), but DC-37 was also an option.
I think DP used 220/330 termination on lines, where Centronics was a simple 1K pullup. There were also differences in signalling--DP has both "ready" and and "online" signals.
When I first encountered the Centronics, I thought that it required OC drivers, but apparently totem-pole was good enough for IBM, something which surprised me.
Most medium-sized line printers around 1980 could be configured for either interface. Otherwise, converters could be purchased inexpensively.
--Chuck
